How can I recreate this diamond cut texture surface like on certain flashlights?
You can do it both ways by model or faking the geometry by using a texture. 

Starting with a plane extrude two edges so that you get a model like:



Add two Array Modifiers to create a grid:



Apply the modifiers and cut out the part you want to use, then scale it so that the tiles get the diamond shape. I've also selected the faces (by similar area) and beveled them Ctrl-B:



Add again an Array modifier and a Curve modifier:



Now you can decide to use it as geometry or bake it to a texture.